Railroad system and method for determining information about a railroad system

ABSTRACT

A railroad system and a method for determining information about the railroad system that has at least one track which is formed from at least two rails, on which railroad vehicles move along the rails, having a device which is electrically connected to the two rails at a connecting point and injects an electric current into the rails. In order to allow information to be determined about the railroad system with little effort, in particular the location of a broken rail and/or the direction of travel of a railroad vehicle, a profile of the current or the corresponding profile of the effective track impedance is detected, while a railroad vehicle is approaching, passing, and moving away from the connecting point. At least one railroad system information item is derived on the basis of the profile.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority, under 35 U.S.C. §119, of Germanapplication DE 10 2005 039 420.5, filed Aug. 16, 2005; the priorapplication is herewith incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a railroad system and to a method fordetermination of information about a railroad system. The railroadsystem has at least one track, which is formed from at least two rails,on which railroad vehicles move along the rails. The system further hasa device which is electrically connected to the two rails at aconnecting point and which injects an electric current into the rails.The invention also pertains to a method for determining information, inparticular about a broken rail, in the railroad system.

Railroad systems are generally known, for example for passenger trains.These generally have a plurality of tracks, which are formed from tworails. Signals to control the trains are arranged along the tracks. Thesignals are driven by safety devices, with respectively adjacent safetydevices interchanging control information. This interchange takes placevia the rails by means of coded data in the form of electrical currentpulses, for which purpose the safety devices are electrically connectedto the two rails.

Furthermore, U.S. Pat. No. 5,769,364 discloses a diagnosis device inwhich two devices, in particular safety devices, interchange informationin the form of pulses via the rails, with the two devices alternatelytransmitting and receiving the information. In this case, the voltagewhich is applied to the two rails by the one device, the current whichis produced by it and the voltage which results from it at the otherdevice are in each case measured. These measurements are used todetermine whether the rails are broken.

One disadvantage in this case is the relatively high degree ofcomplexity and the lack of any capability to localize the broken rail.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a railroadsystem and a method for determination of information about the railroadsystem, which overcomes the above-mentioned disadvantages of theheretofore-known devices and methods of this general type and, by meansof which the information can be determined with little complexity, inparticular the information about the location of a broken rail and/orthe direction of travel of a railroad vehicle.

With the foregoing and other objects in view there is provided, inaccordance with the invention, a railroad system, comprising:

a track formed of at least two rails configured to support railroadvehicles moving thereon;

a device electrically connected to the rails at a connecting point andconfigured to inject an electric current into the rails;

means associated with the device for detecting a profile of the currentor a corresponding profile of an effective track impedance while arailroad vehicle is approaching the connecting point, passing theconnecting point, and moving away from the connecting point; and

means associated with the detecting means for deriving at least onerailroad system information item on the basis of the profile.

In accordance with a further feature of the invention, the derivingmeans is configured to determine a broken rail on the basis of theprofile.

With the above and other objects in view there is also provided, inaccordance with the invention, a method of determining information in arailroad system having a track formed with at least two rails and havingrailroad vehicles moving along the rails. The method comprises:

providing a device with an electrical connection to a connecting pointat the rails of the track;

injecting an electric current into the rails at the connecting point;

detecting a profile of the current, or a corresponding profile of aneffective track impedance, while a railroad vehicle is approaching theconnecting point, passing the connecting point, and moving away from theconnecting point; and

deriving at least one railroad system information item on the basis ofthe profile.

In other words, with regard to the railroad system and with regard tothe method, the solution provides for the profile of the current or thecorresponding profile of the effective track impedance to be detected,while a railroad vehicle is approaching the connecting point, passes itand moves away from it again, and for at least one railroad systeminformation item to be derived on the basis of the profile.

In accordance with an added feature of the invention, the railroadsystem information item is at least one of a state of the track and adirection of travel of the railroad vehicle. In accordance with anotherfeature of the invention, deriving means is configured to determine thestate of the track state on the basis of noticeable rates of change ofthe profile. The changes are considered noticeable when they are outsidea predetermined tolerance band. In the alternative, or in addition, thechanges are considered noticeable when they exceed a predetermined valuewithin a predetermined time interval.

In other words, the railroad system information preferably includes thetrack state and/or the direction of travel of the railroad vehicle.

It is technically simple for the track state to be derived on the basisof noticeable rates of change of the profile.

One simple criterion for noticeable changes is when the changes areoutside a predetermined tolerance band.

Simple noticeable changes occur when they exceed a predetermined valuewithin a predetermined time interval.

In the simplest case, a broken rail can be determined on the basis ofthe profile.

The location of the broken rail is determined with little effort on thebasis of the profile.

In order to form a reference value with little effort, it is proposedthat the profile in the area of the connecting point have an essentiallyconstant value as a maximum value, and for this constant value to beused as a reference value.

The accuracy can be increased if the device is arranged in the area, orin the vicinity of an isolating abutment of the rails.

In order to make integration in existing railroad systems easier, it isproposed that the device transmit electrical current pulses via therails, and that the profile correspond to the amplitudes of the currentpulses in the form of an envelope curve.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin a railroad system and method for determination of information about arailroad system, it is nevertheless not intended to be limited to thedetails shown, since various modifications and structural changes may bemade therein without departing from the spirit of the invention andwithin the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified plan view of a track section of a railroadsystem;

FIG. 2 is a profile of the current plotted against the time for apassing railroad vehicle;

FIG. 3 is a profile similar to FIG. 2, with a railroad vehicle passingin the opposite direction of travel;

FIG. 4 is a profile similar to FIG. 2 with a tolerance band; and

FIG. 5 is a view of a track section similar to FIG. 1, with two devicesfor transmission of current pulses.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures of the drawing in detail and first,particularly, to FIG. 1 thereof, there is shown a track section 1 of arailroad system which is formed from two parallel running rails 2.

A schematically illustrated railroad vehicle 3 is moving along the railsin the direction of the arrow 4. Only two wheels 6 of the railroadvehicle 3 are illustrated in FIG. 1. The wheels 6 are rotatably mountedat the ends of a wheel axle 5. It will be understood that the railroadvehicle 3 in reality has a plurality of wheel axles 5. A device 8 iselectrically connected by way of lines 9 to the two rails 2 at aconnecting point 7. In order to simplify the illustration, the lines 9of the connecting point 7 are shown separated from one another in FIG.1;. In practice, there is no such separation, that is to say theconnections of the lines 9 are located approximately at the same level,seen in the longitudinal direction of the rails 2. The rails 2 of thetrack section 1 each have isolating abutments 9 a, 9 b at the same levelin FIG. 1. The device 8 injects a current I into the rails 2 via avoltage U, with the circuit being short-circuited by the railroadvehicle 3 (axle 5 with wheels 6).

With reference to FIG. 1, the railroad vehicle 3 is moving along therails 2, moving from left to right over the connecting point 7. This isassociated with a change in the effective track impedance as the vehicleapproaches the connecting point 7.

FIG. 2 shows the profile 10 of the current I plotted over the time t asthe railroad vehicle 3 passes by. As can be seen from FIG. 2, theprofile 10 of the current I in this case exhibits noticeable rates ofchange. For example, on passing over the isolating abutments 9 a, thecurrent I changes suddenly from the quiescent current IR to the currentIB (time t1). From there, the current increases continuously to the timetx1, while it reaches its saturation current IK at tx1. When passingover the isolating abutments 9 b at the time ty1, the current I returnsto the quiescent current IR. FIG. 2 shows a typical profile 10 for arailroad vehicle 3 which is moving from left to right (as shown in FIG.1), without there being any broken rail or the like.

On the basis of Ohm's law, the profile 10 of the current I correspondsclosely with the profile 10 of the effective track impedance.

The profile 10 can be used to obtain information (railroad systeminformation) as to the direction of travel in which the railroad vehicle3 is moving.

The breakage of one of the rails 2 virtually always occurs only when arailroad vehicle 3 is moving over the rails 2, so that at least onewheel axle 5 will always have passed over the broken point in thedirection of the connecting point 7. In a corresponding manner, theprofile 10 shown in FIG. 2 changes only to the extent that the current Ifalls below the quiescent current IR to the rest or residual current IRBon passing over the isolating abutments 9 b, as is shown in FIG. 2.

FIG. 3 shows the profile of the current I plotted against the time t fora railroad vehicle 3 passing in the opposite direction of travel. Incontrast with FIG. 2, the current drop below the quiescent current IR tothe residual current IRB now occurs when the last wheel axle 5 of therailroad vehicle 3 has passed over the break in the direction of theisolating abutments 9 a. In this case, the break also results in theresidual current IRB being below the quiescent current IR. At the sametime, it is possible to locate the break on the basis of the profile 10.

There should expediently be two devices 8, arranged in the area of theabutment points 9 a, 9 b, because of the asymmetry (see FIG. 5).

FIG. 4 in each case shows a dashed line 11 following a typical profile10 a above and below the typical profile 10 a. The two lines 11 form atolerance band 11 a. Noticeable changes in a profile 10 occur whenever adetermined profile 10 is outside the tolerance band 11.

A noticeable change in the current I also occurs when a change exceeds apredetermined value within a predetermined time interval. A profile thathas been normalized with respect to the current IK can also be used forevaluation purposes, with the current IK expediently being used as areference value at the same time.

FIG. 5 illustrates a track section 1, which corresponds to that inFIG. 1. In contrast with FIG. 1, there are two protection devices 12,which are connected via connections 13 to railroad signaling devices 14that control the railroad vehicles 3 moving along the rails 2. Theprotection devices 12 each include a device 8 which is connected to therails 2 in the area of the isolating abutments 9 a, 9 b. The devices 8operate as transceivers, which transmit coded data via the rails 2 inthe form of electrical current pulses IP, with one of the two adjacentdevices 8 in each case transmitting, and the other device 8 receiving,alternately.

Only two of these current pulses IP are illustrated schematically inFIG. 2 (somewhat broader in order to illustrate them better). A voltagepulse is applied by the transmitting device 8 to the rails 2 for eachcurrent pulse IP. As can be seen from FIG. 2, the profile 10 of thecurrent I in the case of current pulses IP is the envelope curve of thecurrent pulses IP.

The current pulses IP may, of course, be not only current pulses IP ofcoded data which are present in any case, but also general currentpulses IP which are designed such that it is possible to determine thetrack impedance on the basis of the profile 10 or of the envelope curve.

1. A railroad system, comprising: a track formed of at least two railsconfigured to support railroad vehicles moving thereon; a deviceelectrically connected to said rails at a connecting point andconfigured to inject an electric current into said rails; meansassociated with said device for detecting a profile of the current or acorresponding profile of an effective track impedance while a railroadvehicle is approaching said connecting point, passing said connectingpoint, and moving away from said connecting point; and means associatedwith said detecting means for deriving at least one railroad systeminformation item on the basis of the profile.
 2. The railroad systemaccording to claim 1, wherein the railroad system information item is atleast one of a state of the track and a direction of travel of therailroad vehicle.
 3. The railroad system according to claim 2, whereinsaid deriving means is configured to determine the state of the trackstate on the basis of noticeable rates of change of the profile.
 4. Therailroad system according to claim 3, wherein changes are considerednoticeable when the changes are outside a predetermined tolerance band.5. The railroad system according to claim 3, wherein changes areconsidered noticeable when the changes exceed a predetermined valuewithin a predetermined time interval.
 6. The railroad system accordingto claim 1, wherein said deriving means is configured to determine abroken rail on the basis of the profile.
 7. The railroad systemaccording to claim 6, wherein said deriving means is configured todetermine a location of a break in the rail on the basis of the profile.8. The railroad system according to claim 1, wherein the profile in thearea of the connecting point is set such that it has a substantiallyconstant value as a maximum value, and the value is used as a referencevalue.
 9. The railroad system according to claim 1, wherein said railsare formed with an isolating abutment and said device is disposed in avicinity of said isolating abutment.
 10. The railroad system accordingto claim 2, wherein said device is configured to transmit electricalcurrent pulses with amplitudes via said rails, and the profilecorresponds to the amplitudes of the current pulses in the form of anenvelope curve.
 11. A method of determining information in a railroadsystem having a track formed with at least two rails and having railroadvehicles moving along the rails, the method which comprises: providing adevice with an electrical connection to a connecting point at the railsof the track; injecting an electric current into the rails at theconnecting point; detecting a profile of the current, or a correspondingprofile of an effective track impedance, while a railroad vehicle isapproaching the connecting point, passing the connecting point, andmoving away from the connecting point; and deriving at least onerailroad system information item on the basis of the profile.
 12. Themethod according to claim 11, which comprises determining a broken railas the railroad system information item.
 13. The method according toclaim 11, wherein the railroad system information is at least one of atrack state and a direction of travel of the railroad vehicle.
 14. Themethod according to claim 13, which comprises deriving the track stateon a basis of noticeable rates of change of the profile.
 15. The methodaccording to claim 14, which comprises characterizing changes as beingnoticeable when the changes are outside a predetermined tolerance band.16. The method according to claim 15, which comprises characterizingchanges as being noticeable when the changes exceed a predeterminedvalue within a predetermined time interval.
 17. The method according toclaim 12, which comprises determining a location of a break in thebroken rail on the basis of the profile.
 18. The method according toclaim 11, which comprises setting the profile in the area of theconnecting point to have a substantially constant value as a maximumvalue, and using the value as a reference value.
 19. The methodaccording to claim 11, which comprises placing the device in an area ofan isolating abutment of the rails.
 20. The method according to claim11, which comprises transmitting with the device electrical currentpulses via the rails, and defining an envelope curve as the profilecorresponding to the amplitudes of the current pulses.